Avalanche Forecast
Issued: Feb 4th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs, Persistent Slabs and Wind Slabs.
bchristie,
Avalanche Canada
Continue choosing low consequence terrain to play in. A complex, and generally weak snowpack is forcing us to find fun on mellow slopes.
Summary
Confidence
Moderate
Avalanche Summary
On Thursday, west of Invermere, a large (size 2.5), naturally triggered Deep Persistent Slab avalanche was reported. It was in the alpine, and it's suspected that it was triggered by a combination of windloading, and morning sun warming the slope.
A few large (size 2) persistent slab avalanches were triggered by explosives over the past few days, releasing about 40 cm deep in alpine terrain.
The possibility remains of triggering facets near the base of the snowpack, particularly on shallow, rocky slopes.
Snowpack Summary
Wind slabs of approximately 20 cm thick may linger on a variety of surfaces including previously wind-affected snow, a small layer of surface hoar, and a melt-freeze crust on sun-exposed slopes.
The mid-pack contains two layers that remain a concern. The first is buried about 20 to 40 cm and consists of a layer of surface hoar from early January. The second is a layer of surface hoar, facets, and crust buried about 40 to 60 cm.
A layer from late November is found 70 to 130 cm deep and is part of a generally weak, faceted snowpack.
Snowpack depths range between 80 and 180 cm at treeline, with the shallowest depths found on the eastern edge of the region.
Weather Summary
Saturday Night
Partly cloudy. No new snow expected. Light southwest ridgetop wind. Treeline temperature around -5 °C.
Sunday
Partly cloudy. No new snow expected. Light southwest ridgetop wind, possibility of strong west at very high elevations. Treeline temperature around -3 °C.
Monday
Mostly cloudy. Possible trace of snow expected. Variable moderate ridgetop winds around the region. Possibility of strong west wind at very high elevations. Treeline temperature around -5 °C.
Tuesday
Partly cloudy. Possible trace of snow expected. Moderate southwest ridgetop wind trending to strong at higher elevations. Treeline temperature around -3 °C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
- Surface hoar distribution is highly variable. Avoid generalizing your observations.
- Approach lee and cross-loaded slopes with caution.
- Uncertainty is best managed through conservative terrain choices at this time.
Problems
Deep Persistent Slabs
It remans possible that riders could trigger a weak layer of facets near the base of the snowpack. The most likely area to trigger it is in shallow areas with variable snow depths. Avoid thin and rocky start zones and select routes that avoid traveling through or under large avalanche paths.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Several weak layers sit in the upper and middle portions of the snowpack are at prime depths for human triggering. Stay disciplined and choose low consequence lines, particularly in steep, wind-sheltered terrain where these layers may be most problematic.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Wind slabs may linger in leeward terrain features, particularly where they overlie surface hoar crystals. If triggered, wind slabs could step down to deeper weak layers.
Aspects: North, North East, East, South East, South, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 5th, 2023 4:00PM
